Self-tapping screw, method and dies for making the same and method for joining thin workpieces

The invention claims a 镦 hammers the angle multi-convex blank, is made of a method for self-tapping screw and for connecting With Gongjian (1402 and 1404) and angle multi-convex self-tapping screw of the blank (902), the self-tapping screw presents the satisfying thread by a conical the top and main body part, and enhanced head of the shakeproof porosity. Are made the end of the bolt of the head part and method results between the bolt head (410) and a main body part with a thread conical root (906), wherein cross - sections is arranged at the head (410) is a areas of a deformation of are located at the conical root (906) and a bolt main body intersects the maximum non-circle the area (or convex angle) is section. The shape and thread teeth of the outer diameter (906) has basically fixedly connected with the conical root of the main body part constant and multiple screw ring (the thread) is a through which makes the anchor material is axially and inlet (1405) on the extrusion to guarantee and root having a bolt (902) capable of being fixed on the thin anchor material (1404).